The investigation into Tony Stewart's culpability in a sprint car accident that left a fellow driver dead remains open-ended, although authorities have reiterated that they have not yet found any evidence to suggest criminal intent.
Kevin Ward Jr was killed on Saturday after he ran towards Stewart's car to remonstrate after an on-track incident between the pair and was hit by the three-time Cup champion's right-rear wheel.
Investigators said that the 20-year-old was briefly dragged underneath the car before being flung to the outside of the track.
Although he was wearing a helmet, he died of a massive blunt trauma to the head.
Police have received and reviewed a second video of the accident that was filmed by a spectator, and are reportedly focusing on the degree to which lighting and visibility may have played a part.
The crash happened during a night race, and Ward was wearing a black race suit and helmet.
Ontario County Sheriff Phillip Provero said that the investigation might not be concluded for months, but he added that the early analysis continues to suggest that the crash was an accident.
"This is an open investigation," he said. "What I have said is not indicative that this investigation is over or that conclusions have been made.
"It is open and we are continuing to gather information.
"We continue to be asked about criminal charges. No criminal charges have been placed against anyone, and there are no facts that this point that would support probable cause of any criminal behaviour."
Audio of the accident appears to suggest that Stewart blipped the throttle as he passed Ward, which has prompted speculation that he may have been attempting to give his rival a fright and inadvertently lost control of the rear of his car.
Provero refused to be drawn on whether that could constitute intent to harm Ward, but confirmed that it was being analysed.
"I don't want to get into [intent]," he said. "But regarding that audio, that's part of the information that we're looking at regarding clarity and confirmation."
Stewart has withdrawn from a sprint car race in Indiana that he had been scheduled to participate in this weekend.
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